batches: use user name/e-mail with unauthored batch specs

[adeola-ak]

fixes the E2E test that failed after merge in #43828 and needed to be reverted

Implementing the same fallback behaviour for changeset specs on SSBC that we have on the client side where we try to get the author name and e-mail for commits from the environment if they're not in the batch spec by pulling that from the user's account details and created a sub-package author to do so

Test plan

Tested created a bc in various cases with missing information

[sourcegraph-bot]

Codenotify: Notifying subscribers in CODENOTIFY files for diff 4807df1...706182c.

Notify	File(s)
@bobheadxi	enterprise/dev/ci/integration/executors/tester/main.go
@efritz	enterprise/cmd/worker/internal/batches/workers/batch_spec_workspace_creator.go
@eseliger	enterprise/cmd/worker/internal/batches/workers/batch_spec_workspace_creator.go enterprise/internal/batches/store/author/author.go enterprise/internal/batches/store/author/author_test.go enterprise/internal/batches/store/worker_workspace_execution.go

[sourcegraph-bot]

Codenotify: Notifying subscribers in OWNERS files for diff 4807df1...706182c.

Notify	File(s)
@sourcegraph/dev-experience	enterprise/dev/ci/integration/executors/tester/main.go

[courier-new]

Looks good to me, but could we trigger the executor e2e tests for this PR to double-check before we merge?

[adeola-ak]

@courier-new how can i trigger the executor e2e tests?

[github-actions]

❌ Problem: the label i-acknowledge-this-goes-into-the-release is absent.
👉 What to do: we're in the next Sourcegraph release code freeze period. If you are 100% sure your changes should get released or provide no risk to the release, add the label your PR with i-acknowledge-this-goes-into-the-release.

[courier-new]

From your branch locally you can run sg ci build main-dry-run. You should see the full buildkite suite with executors e2e kick off from that. 🙂

[adeola-ak]

nice, thanks! looks like its good beside security scans

[courier-new]

Awesome thanks! I'll approve to unblock, but I also think there's no rush on this if you want to wait until after 4.4 cut tomorrow.

[adeola-ak]

thank uuu! yes thats what i was thinking, ill just wait